Re: Mach emulation

[Gernot Heiser]

On Sat, 11 Nov 2000 10:33:23 +0900, OKUJI Yoshinori <address@hidden> wrote,

okuji>   This is just a thought. As I said in debian-hurd, Mach emulation on
okuji> L4 would be a good approach to realize how different L4 is from Mach
okuji> and what problems lie in porting Hurd to L4. Obviously, it is quite
okuji> hard to migrate from Mach to L4 suddenly. But once we can run Hurd on
okuji> L4 even in a dirty and slow way, we will be able to get a code base
okuji> which can eventually be used in native mode.

Whether that's a sensible approach depends on what you want from the
port.

If all you want is hurd running on L4, fine. (But why?)

If what you want is hurd to be _fast_, then its a recipe for disaster.

Mach sux because it's too big. Any attempt to emulate Mach on top of
L4 will be just as bad. And migrating drivers out to userland won't
help.

If this is to make sense, hurd needs to be retargeted directly to L4,
not some encapsulation of L4. Essentially, hurd will have to be
directed towards L4 abstractions, rather then Mach abstractions.

Read Liedtke's papers in the '93 and '95 SOSP for more...

If this project is getting serious I might be able to get one or two
of my students to help...

Gernot


Gernot Heiser                ,--_|\   School of Computer Sci. & Engin.
Phone:  +61 2 9385 5156     /      \  The University of NSW
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